1 /* SPDX-License-Identifier: GPL-2.0+ */
2 /*
3 * Read-Copy Update mechanism for mutual exclusion (tree-based version)
4 *
5 * Copyright IBM Corporation, 2008
6 *
7 * Author: Dipankar Sarma <dipankar@in.ibm.com>
8 * Paul E. McKenney <paulmck@linux.ibm.com> Hierarchical algorithm
9 *
10 * Based on the original work by Paul McKenney <paulmck@linux.ibm.com>
11 * and inputs from Rusty Russell, Andrea Arcangeli and Andi Kleen.
12 *
13 * For detailed explanation of Read-Copy Update mechanism see -
14 * Documentation/RCU
15 */
16
17 #ifndef __LINUX_RCUTREE_H
18 #define __LINUX_RCUTREE_H
19
20 void rcu_softirq_qs(void);
21 void rcu_note_context_switch(bool preempt);
22 int rcu_needs_cpu(void);
23 void rcu_cpu_stall_reset(void);
24 void rcu_request_urgent_qs_task(struct task_struct *t);
25
26 /*
27 * Note a virtualization-based context switch. This is simply a
28 * wrapper around rcu_note_context_switch(), which allows TINY_RCU
29 * to save a few bytes. The caller must have disabled interrupts.
30 */
rcu_virt_note_context_switch(void)31 static inline void rcu_virt_note_context_switch(void)
32 {
33 rcu_note_context_switch(false);
34 }
35
36 void synchronize_rcu_expedited(void);
37 void kvfree_call_rcu(struct rcu_head *head, void *ptr);
38
39 void rcu_barrier(void);
40 bool rcu_eqs_special_set(int cpu);
41 void rcu_momentary_dyntick_idle(void);
42 void kfree_rcu_scheduler_running(void);
43 bool rcu_gp_might_be_stalled(void);
44
45 struct rcu_gp_oldstate {
46 unsigned long rgos_norm;
47 unsigned long rgos_exp;
48 };
49
50 // Maximum number of rcu_gp_oldstate values corresponding to
51 // not-yet-completed RCU grace periods.
52 #define NUM_ACTIVE_RCU_POLL_FULL_OLDSTATE 4
53
54 /**
55 * same_state_synchronize_rcu_full - Are two old-state values identical?
56 * @rgosp1: First old-state value.
57 * @rgosp2: Second old-state value.
58 *
59 * The two old-state values must have been obtained from either
60 * get_state_synchronize_rcu_full(), start_poll_synchronize_rcu_full(),
61 * or get_completed_synchronize_rcu_full(). Returns @true if the two
62 * values are identical and @false otherwise. This allows structures
63 * whose lifetimes are tracked by old-state values to push these values
64 * to a list header, allowing those structures to be slightly smaller.
65 *
66 * Note that equality is judged on a bitwise basis, so that an
67 * @rcu_gp_oldstate structure with an already-completed state in one field
68 * will compare not-equal to a structure with an already-completed state
69 * in the other field. After all, the @rcu_gp_oldstate structure is opaque
70 * so how did such a situation come to pass in the first place?
71 */
same_state_synchronize_rcu_full(struct rcu_gp_oldstate * rgosp1,struct rcu_gp_oldstate * rgosp2)72 static inline bool same_state_synchronize_rcu_full(struct rcu_gp_oldstate *rgosp1,
73 struct rcu_gp_oldstate *rgosp2)
74 {
75 return rgosp1->rgos_norm == rgosp2->rgos_norm && rgosp1->rgos_exp == rgosp2->rgos_exp;
76 }
77
78 unsigned long start_poll_synchronize_rcu_expedited(void);
79 void start_poll_synchronize_rcu_expedited_full(struct rcu_gp_oldstate *rgosp);
80 void cond_synchronize_rcu_expedited(unsigned long oldstate);
81 void cond_synchronize_rcu_expedited_full(struct rcu_gp_oldstate *rgosp);
82 unsigned long get_state_synchronize_rcu(void);
83 void get_state_synchronize_rcu_full(struct rcu_gp_oldstate *rgosp);
84 unsigned long start_poll_synchronize_rcu(void);
85 void start_poll_synchronize_rcu_full(struct rcu_gp_oldstate *rgosp);
86 bool poll_state_synchronize_rcu(unsigned long oldstate);
87 bool poll_state_synchronize_rcu_full(struct rcu_gp_oldstate *rgosp);
88 void cond_synchronize_rcu(unsigned long oldstate);
89 void cond_synchronize_rcu_full(struct rcu_gp_oldstate *rgosp);
90
91 #ifdef CONFIG_PROVE_RCU
92 void rcu_irq_exit_check_preempt(void);
93 #else
rcu_irq_exit_check_preempt(void)94 static inline void rcu_irq_exit_check_preempt(void) { }
95 #endif
96
97 struct task_struct;
98 void rcu_preempt_deferred_qs(struct task_struct *t);
99
100 void exit_rcu(void);
101
102 void rcu_scheduler_starting(void);
103 extern int rcu_scheduler_active;
104 void rcu_end_inkernel_boot(void);
105 bool rcu_inkernel_boot_has_ended(void);
106 bool rcu_is_watching(void);
107 #ifndef CONFIG_PREEMPTION
108 void rcu_all_qs(void);
109 #endif
110
111 /* RCUtree hotplug events */
112 int rcutree_prepare_cpu(unsigned int cpu);
113 int rcutree_online_cpu(unsigned int cpu);
114 int rcutree_offline_cpu(unsigned int cpu);
115 int rcutree_dead_cpu(unsigned int cpu);
116 int rcutree_dying_cpu(unsigned int cpu);
117 void rcu_cpu_starting(unsigned int cpu);
118
119 #endif /* __LINUX_RCUTREE_H */
120